"1898-03-25Z"^^ . "David Vernon Widder (25 March 1898 \u2013 8 July 1990) was an American mathematician. He earned his Ph.D. at Harvard University in 1924 under George Birkhoff and went on to join the faculty there.He was a co-founder of the Duke Mathematical Journal and the author of the textbook Advanced Calculus."@en . . . "1990Z"^^ . "American mathematician" . . . . . "1990-07-08Z"^^ . . . "1898Z"^^ . . "Widder, David"@en . . . "David Widder"@en . .